1. Field of the Invention
The present invention relates to a dominant color feature description used in a content-based multimedia data retrieval system, and in particular to a method for setting-up a video region dominant color a data structure therefor, and a method for extracting a confidence measure, which are capable of expressing an object and a color of a ROI (Region Of Interest) in a video during a multimedia indexing operation.
2. Description of the Background Art
In a multi-media search system, there are various methods for expressing a color feature of an object and a ROI of a video in a multi-media search system. The above-described methods are applied differently in accordance with each system.
There are various methods for expressing a dominant color, such as a method for using an average color value of a region, a method for expressing the most frequently appearing color, a method for expressing n-number of the most frequently appearing colors, a method for using a color appearing in a region predetermined by threshold of P % or above, and a method using a color histogram.
Each of the above-described conventional methods has its own advantages and disadvantages. For example, the method of using the histogram has an advantage to describe color information in detail. However, it also has some problems in that the histogram has relatively large size of data and some colors represented by corresponding histogram bins can be considered as they have unnecessary region dominant color values with respect to those colors occupying relatively small regions.
In the case that a region dominant color value is expressed by one average value, there are advantages in that it is a compressed data descriptor and used for pre-filtering in a content-based searching. However, in the case that the region colors are formed in various colors, it is impossible to express the dominant color feature accurately.
Recently, a data structure for extracting the region dominant color is being standardized. However, if a unique method for the extraction of the region dominant color is not standardized and only data structure is standardized, it is impossible to maintain a compatibility of the data built in each system where a plurality of systems are used.
In addition, even when extracting the dominant color values by the same method, it is hard to achieve a reliable performance in every case.
For example, beside the problems presented when the average color is used as a dominant color, when the histogram is used to express the dominant color feature, the performance depends on the number of histogram bins, namely, the number of color levels.
If there are too large number of bins, the region color is unnecessarily expressed by too many colors for thereby decreasing a search performance, and when the region color is expressed by too few colors with a small number of bins, the region formed of various colors is not properly expressed, so that the search performance is degraded.